Rocker Arms and Shafts

The Mitsubishi special tool No. MD 998443 (to retain the hydraulic lash adjusters) should be used before removing the rocker arm/shaft assembly.

Disconnect the negative battery cable. Remove the rocker cover and the upper timing belt cover. Loosen the camshaft sprocket bolt until you can turn it with your fingers.

Fig. Fig. 1: The special tool is used to retain hydraulic lash adjusters

Fig. Fig. 2: Exploded view valve train assembly-2.0L engine

Turn the engine over until the camshaft sprocket timing mark lines up with the timing mark on the cylinder head. The Top Dead Center mark on the front crankshaft pulley must line up with the timing scale on the front cover.

Remove the camshaft sprocket bolt, and without allowing tension on the belt to be lost, place the sprocket in the sprocket holder of the front cover or lower timing belt cover. Make sure you don't lose tension on the belt as this will require a lot of additional labor. Make sure, also, that you do not turn the crankshaft throughout the work. Put the special clips on the eight hydraulic adjusters at the outer ends of all eight rocker arms. Note that these clips go over the lash adjusters that actuate the large intake valves, not on the small adjusting screw for the smaller jet valves.

Loosen but do not remove the camshaft bearing cap bolts (not the outer or cylinder head bolts), rotating them outward in steps, a little at a time, moving from bolt to bolt. Remove the bolts and then, holding the ends so the assembly stays together, remove the rocker shaft assembly from the cylinder head.

To install:

Place the assembly on a clean work bench. Remove the bolts (which retain the bearing caps in position on the shafts) two at a time along with the associated cap, washers, springs and rockers. Continue until all parts are disassembled. Keep all parts in original order. All parts that will be re-used must be in original positions.

Inspection of parts should include verifying that the pads that follow the cam lobes are not worn excessively and that the oil holes are clear. Replace the rockers and/or shafts if rockers are loose on the shafts. If any of the hydraulic lash adjusters have been diagnosed as defective (valves tapping or not closing fully) they can be replaced by removing clips, allowing the adjuster to fall out of the rocker, and replacing the adjuster with another. Install the clip to keep the new adjuster from dropping out of the arm.

Assemble the parts of the rocker assembly as follows:

Install the left and right side rocker shafts into the front bearing cap. Notches in the ends of the shaft must be upward.

Install the bolts for the front cap to retain the shafts in place. Note that the left rocker shaft is longer than the right rocker shaft.

Install the wave washer onto the left rocker shaft with the bulge forward.

Coat the inner surfaces of the rockers and the upper bearing surfaces of the bearing caps with clean engine oil and assemble rockers, springs, and the remaining bearing caps in order. The intake rockers are the only ones with the jet valve actuators. Note that the rockers are labeled for cylinders 1-3 and 2-4 because the direction the jet valve actuator faces changes. Use mounting bolts to hold the caps in place after each is assembled. When the assembly is complete, install it onto the head and start all mounting bolts into the head and tighten finger-tight.

Tighten the attaching bolts for the rocker assembly to 14-15 ft. lbs. (19-20 Nm), working from the center outward.

Without removing tension from the timing chain or belt, lift the sprocket out of the holder and position it against the front of the camshaft. Make sure the locating tang on the sprocket goes into the hole in the front of the camshaft. Install the bolt. Tighten it to 65 ft. lbs. (88 Nm).

Apply sealant to the top surface of the semi-circular seals in the head and install the valve cover. Install the upper timing belt cover.

2.6L Engines

The Mitsubishi special tool No. MD 998443 (to retain the hydraulic lash adjusters) should be used before removing the rocker arm/shaft assembly.

Follow the previously described procedures for removal of the valve cover.

Loosen the large center bolt holding the camshaft sprocket to the camshaft; don't remove it, just loosen it.

Turn the crankshaft pulley clockwise until the timing marks align on both the cylinder head and the crank pulley. This sets the engine at TDC No.1 cylinder. Once this position is established, the engine MUST NOT be rotated during repairs.

Remove the center bolt from the sprocket and remove the small distributor drive gear.

Pull the camshaft sprocket with the chain attached out from the camshaft and place it on top of the camshaft sprocket holder. Do not allow the chain to come off the sprocket.

Loosen but do not remove the camshaft bearing cap bolts (not the outer or cylinder head bolts). Start at an inner or center bolt and work outward in a circular pattern, loosening each a little at a time, moving from bolt to bolt.

Remove the bolts after all are loosened. Hold the ends so the assembly stays together and remove the rocker shaft assembly from the cylinder head.

To install:

Place the assembly on a clean work bench. Remove the bolts (which retain the bearing caps in position on the shafts) two at a time along with the associated cap, washers, springs and rockers. Continue until all parts are disassembled. Keep all parts in original order. All parts that will be re-used must be in original positions.

Inspection of parts should include verifying that the pads that follow the cam lobes are not worn excessively and that the oil holes are clear. Replace the rockers and/or shafts if rockers are loose on the shafts. If any of the hydraulic lash adjusters have been diagnosed as defective (valves tapping or not closing fully) they can be replaced by removing clips, allowing the adjuster to fall out of the rocker, and replacing the adjuster with another. Install the clip to keep the new adjuster from dropping out of the arm.

Install the left and right side rocker shafts into the front bearing cap. The rear end of the left (intake) rocker arm shaft has a notch. Align the mating marks on the front of each rocker shaft to the mating marks on the front bearing cap. Insert the bolts to hold the shafts in the cap.

Install the wave washer so that the rounded side bulges toward the timing chain.

Coat the inner surfaces of the rockers and the upper bearing surfaces of the bearing caps with clean engine oil and assemble rockers, springs, and the remaining bearing caps in order. The intake rockers are the only ones with the jet valve actuators. Note that the rockers are labeled for cylinders 2, 3 and 4. While similar in shape, they must be reinstalled in their original position. Use mounting bolts to hold the caps in place after each is assembled. When the assembly is complete, install it onto the head and start all mounting bolts into the head and tighten finger-tight.

Tighten the attaching bolts for the rocker assembly to 15 ft. lbs. (20 Nm), working from the center outward. Remove the special clips from the rocker arms.

Without removing tension from the timing chain, lift the sprocket out of the holder and position it against the front of the camshaft. Make sure the locating tang on the sprocket goes into the hole in the front of the cam.

Install the distributor drive gear, making certain it is properly seated. Install the sprocket bolt and tighten it finger-tight.

Apply sealant to the flat face of the half-circle plug in the head. Install the valve cover and gasket.

2.4L and 3.0L Engines

See Figures 3, 4 and 5

The Mitsubishi special tool No. MD 998443 (to retain the hydraulic lash adjusters) should be used before removing the rocker arm/shaft assembly.

Follow the previously described procedures for removal of the valve cover.

Fig. Fig. 3: 3.0L engine rocker shaft assembly

Fig. Fig. 4: Correct assembly of rocker shaft assembly-3.0L Engines

Fig. Fig. 5: Directional arrows on the bearing caps must agree with the arrows on the cylinder head assembly

Install the special clips (MB 998443-01) to hold the auto-adjusters in place. Carefully loosen the retaining bolts at each bearing cap. Keep light downward pressure on the rockers to hold the camshaft in place.

When all the bolts are loose, remove them from the front (pulley end) to the rear while keeping the same light pressure on the assembly. Have an assistant hold the camshaft firmly in place as you remove the rocker assembly. The tension of the timing belt will try to pop the camshaft out of its journals; this must NOT be allowed to happen. If this should happen, you'll need to reinstall the camshaft and timing belt. Instructions for each are found later in this section.

As soon as the rocker assembly is clear of the vehicle, remove the rearmost bearing cap and install it in its original position on the cam. Tighten the bolts just snug enough to hold it in place. If, during the inspection process, this bearing cap must be removed for cleaning or replacement, install the No. 3 bearing cap before removing the No. 4 cap.

Take care during removal that no oil, grease or dirt comes into contact with the timing belt.

To install:

Disassemble the rocker assembly, checking each component for wear, scoring, or plugged oil passages. Check the roller for correct and smooth rotation. Inspect the inner diameter of each rocker for any scoring or enlargement. If wear is found inside the rocker, replace it and inspect the shaft for damage.

Before reassembly, coat the contact faces liberally with clean motor oil. Observe the numbers on the bearing caps so that they are replaced in the correct location. Reassemble the rocker shafts into the front bearing cap so that the notches face outward. As you continue to assemble the springs, rockers and bearing caps, remember that the arrows on the bearing caps must point in the same direction as the arrow on the head. This is particularly important if the rockers have been removed from both heads.

When the rocker arm assembly is complete (except for the rear bearing cap, which is holding the camshaft down), have your assistant hold the camshaft while the rear cap is removed. Assemble the last cap onto the rocker assembly and carefully fit the assembly onto the head. Remember that the camshaft must be held in place during this exchange.

Install the retaining bolts finger-tight, making sure each rocker is correctly aligned with the camshaft and valve stem. Once the rockers are securely in place, the special retaining clips may be removed.

Starting at the center bearing cap and working outward in two passes, tighten the bearing cap bolts to 15 ft. lbs. (20 Nm).

Apply sealer to the correct locations and reinstall the valve cover.

3.5L DOHC Engines

The 3.5L DOHC engines are not equipped with rocker arm shafts like the other engines from Mitsubishi. To remove the rocker arms, the camshafts must first be removed. Refer to the procedures for camshaft removal, located later in this section.

2.3L Diesel Engines

Follow the previously described procedures for removal of the valve cover.

Remove the timing belt covers.

Using a wrench, turn the crankshaft in a clockwise direction until all the timing marks align. This positions No.1 piston at TDC/compression.

Remove the 5 flange bolts and washers holding the rocker rail to the head.

Lift the rocker assembly with the rockers attached away from the engine.

To install:

If the assembly is to be disassembled, take note that the intake and exhaust rockers are different. Each is labeled
I
or
E
; they must be reassembled in the correct positions.

Inspect the arms and shafts after a thorough cleaning. The face of the cam follower must be smooth and free of grooves. The end of the adjuster screw must be round (spherical), not mushroomed or flattened. The oil passages in the shaft must be open.

Reassemble the rockers onto the shaft, making certain each component is in the correct location. Coat the entire shaft and rockers with a light coat of clean engine oil. Pay particular attention to coating the face of each cam follower.

Install the assembly onto the head. Install the 5 retaining bolts and tighten them alternately and evenly to 27 ft. lbs. (37 Nm).